scholarly journals Drought Resistance of Norway Spruce (Picea abies [L.] Karst) and European Beech (Fagus sylvatica [L.]) in Mixed vs. Monospecific Stands and on Dry vs. Wet Sites. From Evidence at the Tree Level to Relevance at the Stand Level

Forests ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 639
Author(s):  
Shah Rukh ◽  
Werner Poschenrieder ◽  
Michael Heym ◽  
Hans Pretzsch
Keyword(s):  
Stress Gradient ◽  
Volume Growth ◽  
Ring Width ◽  
European Beech ◽  
Tree Level ◽  
Mixed Stands ◽  
Ecological Gradient ◽  
Individual Tree ◽  
Growth Loss ◽  
The Individual

Frequency of drought years is expected to increase through climate warming. Mixed stands have often shown to be more productive than monospecific stands in terms of yield and of resistance against windthrows and bark beetle attacks. Mixture of beech and spruce is of particular interest. However, little is known about its growth reaction to drought. Therefore, we investigated the drought reaction of beech and spruce in mixed vs. monospecific stands along an ecological gradient. In particular, we sought evidence for mixture-related resilience on the individual tree level. Therefore, we quantified the response of tree ring width to drought. Moreover, we attempted to explain the relevance of individual tree response on the stand level by quantifying the stand level loss of volume growth after drought. At the individual tree level, beech was found to be more resilient and resistant in pure vs. mixed stands. Spruce, in contrast, was favored by mixture, and this was especially evident on drier sites. Along the gradient, growth losses at stand level increased in both mixed and pure stands in 2015, with growth gains on the drier sites observed in the same drought year, in accordance with the Stress Gradient Hypothesis. However, the stand level difference of growth loss between mixed and pure stands was not statistically significant. Mitigating mixture effects on the level of the individual tree thus did not become evident on the level of the whole stand.

scholarly journals Axial changes in wood functional traits have limited net effects on stem biomass increment in European beech (Fagus sylvatica)

2020 ◽  
Vol 40 (4) ◽  
pp. 498-510
Author(s):  
Richard L Peters ◽  
Georg von Arx ◽  
Daniel Nievergelt ◽  
Andreas Ibrom ◽  
Jonas Stillhard ◽  
...  
Keyword(s):  
Fagus Sylvatica ◽  
Carbon Fixation ◽  
Carbon Allocation ◽  
Volume Growth ◽  
Ring Width ◽  
European Beech ◽  
Wood Formation ◽  
Tree Level ◽  
Mature Trees ◽  
Anatomical Basis

Abstract During the growing season, trees allocate photoassimilates to increase their aboveground woody biomass in the stem (ABIstem). This ‘carbon allocation’ to structural growth is a dynamic process influenced by internal and external (e.g., climatic) drivers. While radial variability in wood formation and its resulting structure have been intensively studied, their variability along tree stems and subsequent impacts on ABIstem remain poorly understood. We collected wood cores from mature trees within a fixed plot in a well-studied temperate Fagus sylvatica L. forest. For a subset of trees, we performed regular interval sampling along the stem to elucidate axial variability in ring width (RW) and wood density (ρ), and the resulting effects on tree- and plot-level ABIstem. Moreover, we measured wood anatomical traits to understand the anatomical basis of ρ and the coupling between changes in RW and ρ during drought. We found no significant axial variability in ρ because an increase in the vessel-to-fiber ratio with smaller RW compensated for vessel tapering towards the apex. By contrast, temporal variability in RW varied significantly along the stem axis, depending on the growing conditions. Drought caused a more severe growth decrease, and wetter summers caused a disproportionate growth increase at the stem base compared with the top. Discarding this axial variability resulted in a significant overestimation of tree-level ABIstem in wetter and cooler summers, but this bias was reduced to ~2% when scaling ABIstem to the plot level. These results suggest that F. sylvatica prioritizes structural carbon sinks close to the canopy when conditions are unfavorable. The different axial variability in RW and ρ thereby indicates some independence of the processes that drive volume growth and wood structure along the stem. This refines our knowledge of carbon allocation dynamics in temperate diffuse-porous species and contributes to reducing uncertainties in determining forest carbon fixation.

scholarly journals Growing Space Management in Boreal Mixedwood Forests: 11-Year Results

2011 ◽  
Vol 26 (2) ◽  
pp. 82-90 ◽  
Author(s):  
Richard D. Kabzems ◽  
George Harper ◽  
Peter Fielder
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Light Availability ◽  
White Spruce ◽  
Tree Level ◽  
Mixed Stands ◽  
Individual Tree ◽  
Space Management ◽  
Growing Seasons ◽  
The Individual

Abstract Managing boreal mixed stands of trembling aspen (Populus tremuloides Michx.) and white spruce (Picea glauca [Moench] Voss) is more likely to sustain a diversity of values and has the potential to increase productivity at both the site and landscape levels compared with pure broadleaf or conifer management. In this study, we examine growth of white spruce and aspen after 11 growing seasons over a range of aspen densities created by spot and broadcast treatment of broadleaves using manual and chemical means, aspen spacing, and an untreated control. Results indicate that survival and growth of both spruce and aspen were similar across the range of treatments. Spruce groundline diameter was greater, and height to groundline diameter ratio was lower, for the treatments in which aspen was chemically controlled or uniformly spaced compared with the control. Light measurements at the individual tree level suggested that increased light availability improved white spruce diameter growth. Spruce height growth did not vary by treatment. The status of these experimental mixedwoods was compared with current conifer and mixedwood regeneration evaluations, as well as the preharvest composition of the original stand. After 11 growing seasons, growth of aspen and white spruce indicated that opportunities exist to further modify aspen density to enhance treatment longevity and effectiveness to produce a greater range of boreal mixedwood stand types.

scholarly journals Individual tree measurements by means of digital aerial photogrammetry

2004 ◽  
Vol 2004 (3) ◽  
Author(s):  
Ilkka Korpela
Keyword(s):  
Measurement Errors ◽  
Aerial Photographs ◽  
Tree Level ◽  
Stem Volume ◽  
Species Classification ◽  
Mixed Stands ◽  
Individual Tree ◽  
Crown Width ◽  
The Individual ◽  
Positioning Algorithm

This study explores the plausibility of the use of multi-scale, CIR aerial photographs to conduct forest inventory at the individual tree level. Multiple digitised aerial photographs are used for manual and semi-automatic 3D positioning of tree tops, for species classification, and for measurements on tree height and crown width. A new tree top positioning algorithm is presented and tested. It incorporates template matching in a 3D search space. Also, a new method is presented for tree species classification. In it, a partition of the image space according to the continuously varying image-object-sun geometry of aerial views is performed. Discernibility of trees in aerial images is studied. The measurement accuracy and overall measurability of crown width by using manual image measurements is investigated. A simulation study is used to examine the combined effects of discernibility and photogrammetric measurement errors on stand variables. The study material contained large-scale colour and CIR image material and 7708 trees from 24 fully mapped plots in Southern Finland. The results of the discernibility analysis suggest that 88–100% of the total stem volume is measurable when using multiple aerial photographs. The structure and density of the forest were found to affect discernibility. The best hit-rates when using the semi-automatic tree top positioning algorithm ranged from 77 to 100% of the visually discernible trees. Systematic underestimation of the crown width was observed and the measurability of crown width was best near the image nadir. Species classification was tested in mixed stands of Scots pine, Norway spruce, and silver birch. The Kappa-coefficients ranged from 0.71 to 0.86. The results of the simulation suggest that very high accuracy at the individual tree level cannot be expected. However, if the photogrammetric measurements are unbiased, the aggregate stand variables can be very accurate. An accurate species recognition method is needed in the mixed stands in order to achieve unbiased estimates for the small strata.

scholarly journals SISFLOR: A COMPUTATIONAL SYSTEM TO DETERMINE THE OPTIMAL TREE BUCKING

2020 ◽  
Vol 28 ◽  
pp. 192-201
Author(s):  
Rodrigo Freitas Silva ◽  
Marcelo Otone Aguiar ◽  
Mayra Luiza Marques Da Silva ◽  
Gilson Fernandes Da Silva ◽  
Adriano Ribeiro De Mendonça
Keyword(s):  
Optimization Technique ◽  
Wood Products ◽  
Tree Level ◽  
Economic Losses ◽  
Computational System ◽  
Individual Tree ◽  
Optimal Tree ◽  
Cutting Pattern ◽  
Forest Enterprises ◽  
The Individual

A continuously competitive forest market and tied to the demands for wood products promotes the study and development of applications that increase the revenue of the forest enterprises. At harvesting, the cutting pattern (forest assortment) in which the trees are traced is traditionally determined by the experience of the chainsaw operator without using any optimization technique, which may result in economic losses in relation to the commercialized products. In general, there are numerous distinct assortments that can be chosen and hardly processed by a brute-force algorithm. This is the forest assortment problem at the individual tree level with the objetice of maximizing the commercial values of the felled trees. stem-level bucking optimization problem. The aim is to maximize the sales value of harvested trees. Dynamic Programming (DP) is an efficient optimization technique to determine the optimum bucking tree as it significantly reduces the number of calculations to be made. Thus, the objective of this work was to develop a modern and intuitive computational system that is able to find the optimum tree stem bucking through DP to help companies over the bole tracing, therefore, characterizing itself as a tool that supports decision making. After the execution of the system, the optimum assortment is shown by sequentially detailing all products that should be removed from the analyzed bole as well as their respective volumes and revenue.

scholarly journals Finer Resolution Estimation and Mapping of Mangrove Biomass Using UAV LiDAR and WorldView-2 Data

Forests ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 871 ◽  
Author(s):  
Qiu ◽  
Wang ◽  
Zou ◽  
Yang ◽  
Xie ◽  
...  
Keyword(s):  
Tree Level ◽  
Inference Method ◽  
Mangrove Species ◽  
Individual Tree ◽  
Model Method ◽  
Lower Accuracy ◽  
Field Samples ◽  
The Individual ◽  
Mangrove Biomass ◽  
Grid Based

To estimate mangrove biomass at finer resolution, such as at an individual tree or clump level, there is a crucial need for elaborate management of mangrove forest in a local area. However, there are few studies estimating mangrove biomass at finer resolution partly due to the limitation of remote sensing data. Using WorldView-2 imagery, unmanned aerial vehicle (UAV) light detection and ranging (LiDAR) data, and field survey datasets, we proposed a novel method for the estimation of mangrove aboveground biomass (AGB) at individual tree level, i.e., individual tree-based inference method. The performance of the individual tree-based inference method was compared with the grid-based random forest model method, which directly links the field samples with the UAV LiDAR metrics. We discussed the feasibility of the individual tree-based inference method and the influence of diameter at breast height (DBH) on individual segmentation accuracy. The results indicated that (1) The overall classification accuracy of six mangrove species at individual tree level was 86.08%. (2) The position and number matching accuracies of individual tree segmentation were 87.43% and 51.11%, respectively. The number matching accuracy of individual tree segmentation was relatively satisfying within 8 cm ≤ DBH ≤ 30 cm. (3) The individual tree-based inference method produced lower accuracy than the grid-based RF model method with R2 of 0.49 vs. 0.67 and RMSE of 48.42 Mg ha–1 vs. 38.95 Mg ha–1. However, the individual tree-based inference method can show more detail of spatial distribution of mangrove AGB. The resultant AGB maps of this method are more beneficial to the fine and differentiated management of mangrove forests.

Flexible open-source software for modelling wind disturbance and damage to trees and forests

2020 ◽  
Author(s):  
Tom Locatelli ◽  
Sophie Hale ◽  
Bruce Nicoll ◽  
Barry Gardiner
Keyword(s):  
Risk Model ◽  
Mechanistic Model ◽  
Wind Damage ◽  
Tree Level ◽  
Projection Data ◽  
Wind Disturbance ◽  
Experimental Conditions ◽  
Individual Tree ◽  
Tree Stability ◽  
The Individual

<p>Wind disturbance to forests extends across spatial and temporal scales and encompasses direct and indirect wind effects on the dynamics of forest ecosystems. It is detrimental to the provision of ecosystem services and reduces forest resistance and resilience to future natural disturbances. Historically, in the ecological and land-use scientific communities, forecasting the extent and probability of wind disturbance to forests has represented a serious challenge, with most studies electing to adopt qualitative or statistical approaches. The low degree of portability of statistical assessments of vulnerability to wind has limited their applicability and use, but it is recognised that they have a role in building hypotheses of the processes involved in wind damage that can be subsequently tested under experimental conditions. Results from tree stability experiments have contributed, in the last two decades, to the development of a mechanistic model of wind damage - ForestGALES. This is a process-based wind risk model that was originally created to inform the management of commercial forest plantations in the UK. Built on principles of forest science, physics, and ecology, ForestGALES requires a simple set of inputs and it has now been expanded to cover more than 20 common conifer species from across three continents, and multiple broadleaved species (e.g. Oak, Beech, Birch, and Eucalypts). Two methods of assessing vulnerability to wind damage are available in ForestGALES, one designed for application at stand level, and a novel approach that estimates vulnerability to wind at the individual tree within a stand – the latter allowing for use in complex forest stands, and for the effect of competition between trees in a stand. Until recently, ForestGALES was only available as desktop software and as an online tool as part of forest decision support systems (only for selected countries and species). These formats can be limiting for research and academic projects that aim to model and understanding wind disturbance dynamics across diverse landscapes, and that require a bespoke approach with a high degree of flexibility. To accommodate these broader requirements, ForestGALES has recently been redeveloped and released as a FOSS R package (“<em>fgr</em>”) that is fully customisable and easily integrated in R and modelling workflows and FOSS GIS frameworks. With this poster we present two exemplar studies of assessing wind damage risk to forested landscapes, one for each ForestGALES method (stand- and individual trees level), to showcase the capabilities and flexibility of the model in working with e.g. climate projection data, with other process-based models (e.g. 3PG) within an R modelling framework, and with LiDAR data, at the individual tree level.</p>

Agrilus auroguttatus exit hole distributions on Quercus agrifolia boles and a sampling method to estimate their density on individual trees

2012 ◽  
Vol 144 (6) ◽  
pp. 733-744 ◽  
Author(s):  
Laurel J. Haavik ◽  
Tom W. Coleman ◽  
Mary Louise Flint ◽  
Robert C. Venette ◽  
Steven J. Seybold
Keyword(s):  
Southern California ◽  
Tree Level ◽  
Reliable Estimate ◽  
Hole Density ◽  
Exit Hole ◽  
Individual Tree ◽  
Quercus Agrifolia ◽  
Goldspotted Oak Borer ◽  
The Individual ◽  
Agrilus Auroguttatus

AbstractIn recent decades, invasive phloem and wood borers have become important pests in North America. To aid tree sampling and survey efforts for the newly introduced goldspotted oak borer, Agrilus auroguttatus Schaeffer (Coleoptera: Buprestidae), we examined spatial patterns of exit holes on the boles (trunks) of 58 coast live oak, Quercus agrifolia Née (Fagaceae), trees at five sites in San Diego County, southern California, United States of America. Agrilus auroguttatus exit hole densities were greater at the root collar than at mid-boles (6.1 m above ground). Dispersion patterns of exit holes on lower boles (≤1.52 m) were random for trees with low exit hole densities and aggregated for trees with high exit hole densities. The mean exit hole density measured from three randomly chosen quadrats (0.09 m2) provided a statistically reliable estimate of the true mean exit hole density on the lower bole, with <25% error from the true mean. For future sampling and survey efforts in southern California oak forests and woodlands, exit hole counts within a 0.09 m2 quadrat could be made at any three locations on lower Q. agrifolia boles to accurately estimate A. auroguttatus exit hole densities at the individual tree level.

scholarly journals Species Mixing Effects on Forest Productivity: A Case Study at Stand-, Species- and Tree-Level in the Netherlands

Forests ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 713 ◽  
Author(s):  
Huicui Lu ◽  
Godefridus Mohren ◽  
Miren del Río ◽  
Mart-Jan Schelhaas ◽  
Meike Bouwman ◽  
...  
Keyword(s):  
Forest Management ◽  
Soil Fertility ◽  
Basal Area ◽  
Tree Level ◽  
Stand Age ◽  
Forest Plot ◽  
Mixed Species ◽  
Mixed Stands ◽  
Individual Tree ◽  
Species Mixtures

Many monoculture forests have been converted to mixed-species forests in Europe over the last decades. The main reasons for this conversion were probably to increase productivity, including timber production, and enhance other ecosystem services, such as conservation of biodiversity and other nature values. This study was done by synthesizing results from studies carried out in Dutch mixed forests compared with monoculture stands and evaluating them in the perspective of the current theory. Then we explored possible mechanisms of higher productivity in mixed stands, in relation to the combination of species, stand age and soil fertility, and discussed possible consequences of forest management. The study covered five two-species mixtures and their corresponding monoculture stands from using long-term permanent forest plots over multiple decades as well as two inventories (around 2003 and 2013) across the entire Netherlands. These forest plot data were used together with empirical models at total stand level, species level and tree level. Overyielding in Douglas-fir–beech and pine–oak mixtures was maintained over time, probably owing to the intensive thinning and was achieved on the poorer soils. However, this overyielding was not always driven by fast-growing light-demanding species. On individual tree level, intra-specific competition was not necessarily stronger than inter-specific competition and this competitive reduction was less seen at lower soil fertility and dependent on species mixtures. Moreover, size-asymmetric competition for light was more associated with tree basal area growth than size-symmetric competition for soil resources. Overall, this study suggests a substantial potential of species mixing for increasing productivity and implies developing forest management strategies to convert monospecific forests to mixed-species forests that consider the complementarity in resource acquisition of tree species.

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